Quick Fire Cases
Offdan D. Narvaez-Guerra, MD
Imaging fellow
Medstar Washington Hospital Center
Offdan D. Narvaez-Guerra, MD
Imaging fellow
Medstar Washington Hospital Center
Anam Waheed, MD
Assistant Professor, Georgetown University; Multimodality Imaging Cardiologist
Medstar Washington Hospital Center
Ricardo Nieves, MD
Physician
Medstar Heart and Vascular Institute, Division of Cardiology, Medstar Washington Hospital Ceneter/ Georgetown University
Patrick T. Bering, MD
Physician
Medstar Washington Hospital Center
Gaby Weissman, MD
Physician
Medstar Washington Medical Center
A 78-year-old woman with history of coronary artery disease, coronary artery bypass grafting 13 years prior to presentation, and atrial fibrillation with multiple cardioversions and a recent pulmonary vein isolation procedure, presented from an outside hospital to our institution with signs and symptom consistent with acute decompensated heart failure. A chest x-ray showed bibasilar infiltrates, and a computed tomography (CT) ruled out anatomical pulmonary vein stenosis. A transthoracic echocardiogram revealed a normal left ventricular ejection fraction without regional wall motion abnormalities, with grade III diastolic dysfunction. Cardiac magnetic resonance imaging (CMR) was performed to further characterize cardiac function.
Diagnostic Techniques and Their Most Important Findings:
While obtaining localizer images on CMR, image distortion located in the lower third of the chest slightly to the right of the midline was noted and was characterized by a large area of signal loss and pileup (panels A, B). Given the unknown nature of the object causing the artifact, the decision was made to abort the study and review prior imaging studies. A chest CT performed to rule out pulmonary vein stenosis revealed the presence of a highly attenuating, curvilinear C-shaped object located at the superior vena cava – right atrial junction, within the pericardial space, and with its tips pointing away from the right atrial walls (panels E, F). At this same level, a punctate hyperechogenic spot was present on a prior transesophageal echocardiogram performed to rule out left atrial appendage thrombus (panel G). Additionally, review of the initial chest x-ray showed that the object had a superior pointing end and an inferior blunt end. Findings were most consistent with a retained sewing needle, previously unrecognized.
Learning Points from this Case:
Small metallic objects with a high content of ferromagnetic substances (e.g. iron, nickel), as seen in surgical sewing needles, can produce large artifacts and typically display a “four leaf clover” pattern as the object becomes magnetized and acts as a dipole aligned the magnetic field, leading to inhomogeneity of suppression as well as enhancement of the local field1 (panels C, D). The extent of these artifacts is greater in steady state free precession cine images and can be reduced in size by utilizing gradient-echo MR sequences. Following standardized institutional protocols and pre-CMR checklists is of utter importance. Nonetheless, small retained metallic objects in unusual locations may not be identified on initial imaging. Therefore, timely recognition of unexpected off-resonance artifacts should prompt consideration of patient’s safety in view that objects with high content of ferromagnetic materials can result in object heating and/or migration with damage to surrounding soft tissues.
